new dataset ingestion process

[HeatherSavoy-USDA]

It would be nice to have either a (partially) automated new dataset creation process or at least some checks on a dataset catalog entry. One, it could save some time/work in expanding the library (plus it would be nice to steam metadata along with data when we access remote data). But also reduce errors: I just ran into the issue of testing #14 during which I requested PRISM to be 8000 m resolution. I'm used to PRISM being described as 4 km, I double-checked it was entered into the catalog as 4000 m, but the .bil in my testing data is actually in 0.04166667 degrees - so that explains why I got back one cell in my test. I may or may not have the intended version of PRISM in my local data for testing (we will likely standardize this in #29), but similar errors could happen down the line as we expand the library.